"Until now, research has relied on asking parents when their child reached developmental milestones. But that can be really difficult to recall, and there is a phenomenon called the "telescoping effect" where people usually say that they remember something happening more recently than when it occurred," Ozonoff said. In addition parents frequently will turn off the video camera when their children are behaving poorly - precisely when autistic symptoms may appear.

Ozonoff said that the study provides a deeper understanding for parents, caregivers and health-care providers and for future research of the developmental trajectory for very young children with autism.

"We need to be careful about how we screen, and we need to know what we're looking for," Ozonoff said. "This study tells us that screening for autism early in the first year of life probably is not going to be successful because there isn't going to be anything to notice. It also tells us that we should be focusing on social behaviors in our screening, since that is what declines early in life."

"This study also found that the loss of skills continues into the second and third year of life," she said. "So it may not be adequate, as the American Academy of Pediatrics currently suggests, that providers screen for autism twice before the end of the second year. Autism has a slow, gradual onset of symptoms, rather than a very abrupt loss of skills."

"Screening may need to continue into the third year of life, since symptom emergence takes place over a long time. If a child starts exhibiting a declining trajectory and a sustained reduction in social communication we want to refer them into therapy, especially if they are at risk," Ozonoff said, "even before we might be able to make a definitive diagnosis."

Ozonoff said that the study does not address the etiology of autism or causality. In this study, the infants who participated were at high risk due to having strong family histories of autism, suggesting that genetics play a major role in the later autism diagnoses, despite the fact that their symptoms were not apparent at birth.

Source: University of California - Davis - Health System